DISSERTATION RESEARCH: Vegetation structure constraints on ANPP in arid ecosystems: Assessing the meristem limitation hypothesis

论文研究：干旱生态系统中植被结构对 ANPP 的限制：评估分生组织限制假说

• 批准号: 0910027
• 负责人: Osvaldo Sala
• 金额: $ 1.48万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0910027&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Vegetation; structure; constraints

Although annual precipitation is considered the major control of plant production in arid and semiarid ecosystems it accounts for only 20-40% of the interannual variability of plant production. This doctoral dissertation project is based on the hypothesis that precipitation is indeed an important control but that there are lags in the ecosystem response to changes in precipitation that mask the precipitation-productivity relationship. The student will explore the role of meristem (plant tissue capable of dividing and giving rise to new organs) limitation in creating those lags with a manipulative experiment of incoming precipitation using a combination of passive rainout shelters and irrigation in the Chihuahuan Desert in New Mexico. The experimental design creates sequences of dry and wet years and will elucidate whether there is meristem limitation, whether the magnitude of the limitation is proportional to the rainfall deviation and finally whether the effects of preceding dry years are similar but of opposite sign of the effect of wet years. Results from this project will contribute to the understanding of the effect of climate variability on carbon sequestration, primary production, cattle production and the process of shrub encroachment, issues important to everyone from cattle ranchers to city governments concerned about water supplies. Such stakeholders are interested in understanding the consequences of expected climate change (increased temperature, decreased precipitation, and increased interannual variability) on the ability of their land to provide ecosystem services on which their well-being depends.

尽管在干旱和半干旱生态系统中，年降水量被认为是植物生产的主要控制因素，但它只占植物生产年际变化的20%-40%。这一博士论文项目的基础假设是，降水确实是一个重要的控制因素，但生态系统对降水变化的反应存在滞后，掩盖了降水与生产力的关系。该学生将在新墨西哥州奇瓦瓦沙漠利用被动避雨棚和灌溉相结合的操纵性实验，探索分生组织(能够分裂和产生新器官的植物组织)限制在创造这些滞后中的作用。试验设计创建了干旱年和多雨年的序列，并将阐明是否存在分生组织限制，限制的幅度是否与降雨量偏差成正比，以及之前干旱年的影响是否与多雨年的影响相似但符号相反。该项目的结果将有助于理解气候变化对碳汇、初级生产、牲畜生产和灌木侵蚀过程的影响，这些问题对从养牛农场主到关注供水的市政府每个人都很重要。这些利益攸关方有兴趣了解预期气候变化(气温升高、降水量减少和年际变异性增加)对其土地提供其福祉所依赖的生态系统服务的能力的影响。